I'm not sure what you mean by 'the whole story', books are well known for having an infinite amount of sequels with no real 'conclusion', I don't see how this is any different. It's like complaining that [lotr spoiler]frodo didn't throw the ring into the fires of mount doom until 'return of the king', 2 years after the 'fellowship of the ring'[/lotr spoiler], there is still plenty of story on how that came to be so it's silly to neglect the whole franchise because the conclusion took a while to get to. Really if you are to complain about anything, it shouldn't be a lack of a 'conclusion', rather it should be a lack of substance within the story so far, if you weren't happy with it.